The invention relates to a flexible sleeve type connecting structure especially for connecting a weigh hopper which is movable, to stationary structural components. Connecting devices of this type must satisfy a plurality of requirements, for example, they must be flexible and remain fully operable over a wide temperature range. Additionally, such connecting devices must be capable of taking up pressure shocks that may occur under the operating conditions to which such connecting devices are exposed. The present connecting device is especially suitable to connect the inlet and the outlet of a weigh hopper to respective stationary structural components.
It is known to make the flexible sleeve type portion of such connecting devices of a webbing material having a high tearing resistance, whereby the webbing is coated on both sides by a suitable coating material.
In connection with bulk scales which are used, for example, in coal dust processing plants or plants for handling other dusts capable of exploding, it is necessary to satisfy certain safety requirements. Thus, the flexible connections to the weigh hopper inlet and to the weigh hopper outlet must be capable of taking up explosion pressure shock loads, for example, up to a maximum of ten bar gauge pressure which may occur when a batch of coal dust explodes. In addition, the flexible sleeve type connections must be capable of avoiding the introduction of loads into the scale which would falsify the weight ascertained by the scale. In other words, the shunting of undesired loads or forces into the scale must be avoided by these flexible sleeve type connections in order to satisfy the technical weighing conditions and to assure precise weighing results. The requirements must be met regardless of the type of undesirable loads that must be kept from affecting the weighing result.
Scales, especially continuous feeding scales and batch weighing scales are conventionally installed in structures including large volume supply containers. Different loads applied to these structures may result in bowing or sagging of elements of the structure. Such bowing or sagging may result in permanent deformations of the structure. However, the just described phenomena must not result in the introduction of load components into the scale which would falsify the weighing result. Therefore, the flexible connections disclosed herein must avoid such transmission of undesired force components into the respective scale.
Additionally, the flexible connecting devices must be fully operational over a temperature range extending from normal environmental temperatures to up to 200.degree. C. for example. The flexible, heat resistant, connection must also be gas and liquid tight.
Different versions of such flexible connecting devices are known in the art, for example, folding flexible sleeve type systems made of metal and rubber as well as fabric sleeves and membranes have been used for these purposes. A known flexible sleeve type arrangement comprises, for example, a webbing which is coated on both sides and has a high tearing resistance. Such a webbing is provided with cylindrical end portions, or rather connecting members. However, the actual connection of such a flexible sleeve is rather involved and hence expensive. Besides, such a structure is not suitable for taking up pressures because the connecting points of the flexible sleeve become loose and start to leak. Further, all prior art flexible connecting devices do not satisfy the requirements that must be met by connecting devices for weigh hoppers employed for handling, for example pulverized coal, whereby these connecting devices must take up pressures of up to ten bar and must be heat resistant at temperatures to about 200.degree. C.